Method of separating fumable metals by fractional distillation.



J. THOMSON.

METHOD OF SEPARATING FUMABLE METALS BY FRACTIONAL DlSTlLLATlON. APPUCATION FILED FEB8.1916.

Patented Dec. 12, 1916.

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0F JERSEY CITY, NEW JERSEY,

Specification of Letters Fatent.

Patented Dec. 11%, llfi lltiu application filed February ti, 1M0. taerial Ito. $0,903.

To all tvitom it may concern."

l Be 1t miown that l Jenn TnoMsoN, a citizen of the United gtates, and a resident of the borough of Manhattan, cit of New York, county and State of New orlr, have lnvented certain new and useful improvements in Methods of Separating Fumable Metals by Fractional Distillation, of which the following is a specification, reference bemg made to the accompanying drawing, forming a part thereof.

This invention pertains to metallurgy and particularly to that group of non-ferric metals, in common commercial use, capable of being fumed or vaporized at a comparatively moderate temperature, such for example as nine, lead, antimony, cadmium, etc., and one object of the invention is to separate an alloyed compound of metals into its constituent elements.

The accompanying drawings, which form a part of this specification, have been prepared to illustrate the dominant principles rather than the precise details of means for realizing the invention.

Tn sald drawings Figure l is a vertical, transverse center section, taken as on the plane indicated by line A, in Fig. 2, of an electric furnace adapted for use in the performing of the invention, and Fig, 2 is a plan. view of the furnace shown in Fig. ig. 2 is a View taken as on the plane indicated by line B, in Fig. l, the cover 0 and also the central vertical septum U (see F ig. 1) being removed.

The end and side walls of the furnace E form a common chamber in which is an open tanli F having a central partition 3 which has the eifect of forming two parallel basins, or containers, d, 5 in which are two baths of metal 6, 'l. Resting upon the top of the partition is a non-heat conductive refractory wall or vertical septum D whose upper edge is in contact with the cover C, thereby forming two parallel chambers H, T. In each of these chambers 13 a carbon resistor J, P, here shown as of the slotted zig-zag type, whose terminals are in the electric power-circuits indicated by 8 and 8. ln each side-wall is a tube, as 9, 10 leading from the chambers to the exterior, and 1n the cover is an opening 12 which may be closed or opened at will. Along the upper edge of the partition 3 are a plurality of 55 shallow depressions, as 13, it, hemfi when the overlying septum is in place they in fact form ports or ducts. Q

It willbe conducive to brevity to focaliae the descrlption of this method and its means of real zation upon an alloy of two metals, for which purpose that of zinc and cadmium Wlll be selected.

Y The nominal temperature required to boil Zn is usually taken as being 930 t1, while that of Cd is 780; difierence, 150. The word, nominal is here employed to indicate that these temperatures may be, and in regular practice are, somewhat variable, as when the two metals are alloyed, and they are also responsively variable to conditions of pressure.

The method and means which are the basis of this invention essentially involve, firstly, simultaneously heating two baths of fumable metals at or about the boiling temperatures of each metal; secondly, charging the alloy only to the basin which is acted upon by the lesser temperature; thirdly, supplying the basin which requires the greater temperature wholly from the basin containing metal at a lower temperature; fourthly, causing the metal in both basins to fume or vaporize by electrically incited resistors whose heat is uniformly transferred to the upper surfaces of the baths by radia tion, and, fifthly, separately leading oil and condensing from each bath the fume developed thereat.

As illustrative of the manner in which the invention may be practically performed, let it be assumed that the low of heat is such that resistor d imparts a uniformly distributed temperature of about 950 (1.,

upon all portions of the face of its uriderlying bath, and that resistor F produces a similar efiect upon its underlying bath but with a temperature limited to about 780 to 800 C. The consequence of this is that cadmium will be vaporized and, rising into chamber ll, will pass out therefrom as indicated by arrow 8 to a place where it will be condensed by any suitable means; also zinc will be vaporized and, rising into chamber ill, will pass out therefrom as indicated by arrow m to a place where it will be condensed. From time-to-time, or continuously as the case may be, the alloy, preferably pre-fused or in liquid form, is charged as through the cover-opening 19 into the bath '3' of lesser temperature. The charging into the bath 7 raises its level so that there will be a flow from its surface-from which any contained Cd will have been exhaustedthrough the ports into the bath 6 as indicated by arrow '11. Hence, it is simply necessary to see that during the charging operation the level of the bath 6 shall be some what below that of bath 7 so as to insure a free flow.

If desired, the connecting ducts may read ily be formed as siphons or traps whereby to interpose a seal of liquid metal against any inter-flow of fume; but as the aggregate area of the ducts or ports is insignificant with respect to the volumes of vapor developed such a refinement is not deemed necessary of illustration.

The energy required for this plural vaporizing operation is only. at the most a trifle greater, in sum, than would be expended were both vaporizing operations conducted as one, because the heat imparted to the metal in basin 5 is conveyed to the bath in basin 4.

Bearing in mind that the amount of Cd usually contained in commercial spelter is relatively small, say from 0.15 to 0.50 per centum, and that the interim for its evolution is that required for the vaporization of the much greater volume of Zn, it, will be apparent that the opportunity here aiforded for its removal or evacuation is all that could be desired.

,The results just set forth with respect to an alloy of zinc and cadmium may equally apply to other combinations, such as an alloy of lead and zinc, when the latter, having the lower boiling point, would first be vaporized.

Various modifications may be made in the means for carrying this method into effect. For example, the surface areas of the baths need not necessarily be alike, nor is it essential that the zigzag type of resistor be employed; yet the latter is regarded as the best form of resistor since it possesses the important feature of being capable of operation with slight variation in temperature during long periods of time. The zig-zag resistors might also be run in series so as to use only one electric circuit; but in that case the resistor over the low temperature bath would be so designed as to have a substantially lower resistance than that over the high temperature bath. So, too, the means here shown of charging through the cover may be substituted by a spout having its inner end submerged whereby to convey the colder and denser alloy to the bottom of the bath. Also it is quite feasible to have more than two baths; as. for example, three or four or even more baths whereby to simultaneously treat complex alloys. In such instance, if the combination were cadmium, zinc and lead, then the operation would be as herein described but with an additional basin into which the lead would be caused to flow from the intermediate basin.

\Vhat I claim is:

1. The method of separating alloyed metals, each having a diiferent vaporizing point, which consists in first fuming the metal which vaporizes at the lower temperature and then causing the residuum to flow into another contiguous basin where it is acted upon and vaporized by a higher temperature.

2. The method of separating alloyed metals, each having a different vaporizing point, which comprise charging a container with the alloy; heating the alloy until the metal having the lowest vaporizing temperature is evolved; displacing the residuum by additional charges of alloy and causing it to pass into a contiguous container; volatilizing the metal passed to said last mentioned container and separately condensing the fumes thus fractionally produced.

This specification signed and witnessed this 7th day of February, A. D. 1916.

JOHN THOMSON. Signed in the presence of- J. R. AGNEW, FRED KUBLER. 

